code: def test_check_labels_positive_notok():
      y = np.array([1, 1, -1])
      cl = BlankClassifier(print_progress=0, random_seed=1)
      with pytest.raises(AttributeError) as excinfo:
          cl._check_target_array(y)
          assert excinfo.value.message == (
              "y array must not "
              "contain negative "
              "labels.\nFound [-1  1]"
          )
  
file_path: mlxtend/mlxtend/_base/tests/test_classifier.py
imports: import numpy
  import pytest
  from mlxtend._base import _BaseModel, _Classifier
label_desc: Use image node_id 6 for calling a global function with example usage: test_check_labels_positive_notok() without return types